Current technology for chemical sensing at actionable levels involves costly laboratory instrumentation or expensive field instruments, and provides information over limited spatial extent with often excessive time delay. Existing systems thus tend to be bulky, discrete in nature, location specific, and cost, labor, and time intensive, and are at best inefficiently or ineffectively integrated together, such that they fail to efficiently provide multiple types (such as spectrofluorometry, spectrophotometry, and turbidity) of measurements within a unified or single instrument.
Flowcells are commonly used in spectrofluorometry and spectrophotometry measurements. Commercially available flowcells for spectrofluorometry (fluorescence) measurement usually consist of an excitation optical junction and a detecting optical junction instrumented perpendicular with respect to each other, with the intention to minimize undesirable excitation wavelengths from overlapping with fluorescence wavelengths reaching a detector. On the contrary, spectrophotometry measures the absorbance of the liquid sample in interest; as such, the excitation and detecting optical junctions are instrumented relative to one another with respect to a common or shared axis.
Most commercially available in-situ fluorometers use a single UV excitation source for inducing fluorescence. The setup is favorable in term of sensor packaging and simplicity. However, in the absence of multi-excitation, it does not permit excitation-emission matrix spectroscopy, and also posts limitations to the sensor's ability in separating individual spectra of a complex mixture. For lab-based sensors, the multi-excitation fluorescence measurements have been performed using a single excitation source comprising multiple wavelengths (e.g., Deuterium Tungsten) and a long-pass filter system or a monochrometer to select the wavelength of interest, one at a time, for inducing fluorescence. These added components are usually bulky, heavy, and expensive, rendering an instrument unsuitable for in-situ chemical sensing. Another limitation is that fluorescence and absorbance measurements are seldom made into a single instrument, despite the two differing only in the orientation of the excitation source.
A need exists for fluid sensing or characterization devices, apparatuses, and systems that overcome one or more of the preceding limitations.